[factory] Always tenure external strings

Since external strings are used for things like source strings, we
should tenure them from creation.

Change-Id: I226ab9036836d76d8c17ed168ad97d7f0f824278
Reviewed-on: https://chromium-review.googlesource.com/1006961
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52677}

src/heap/factory.cc

@@ -1151,7 +1151,7 @@ MaybeHandle<String> Factory::NewExternalStringFromOneByte(
     map = external_one_byte_string_map();
   }
   Handle<ExternalOneByteString> external_string(
-      ExternalOneByteString::cast(New(map, NOT_TENURED)), isolate());
+      ExternalOneByteString::cast(New(map, TENURED)), isolate());
   external_string->set_length(static_cast<int>(length));
   external_string->set_hash_field(String::kEmptyHashField);
   external_string->set_resource(resource);
@@ -1183,7 +1183,7 @@ MaybeHandle<String> Factory::NewExternalStringFromTwoByte(
                       : external_string_map();
   }
   Handle<ExternalTwoByteString> external_string(
-      ExternalTwoByteString::cast(New(map, NOT_TENURED)), isolate());
+      ExternalTwoByteString::cast(New(map, TENURED)), isolate());
   external_string->set_length(static_cast<int>(length));
   external_string->set_hash_field(String::kEmptyHashField);
   external_string->set_resource(resource);

test/cctest/test-api.cc

@@ -788,6 +788,7 @@ THREADED_TEST(NewExternalForVeryLongString) {
 
 
 THREADED_TEST(ScavengeExternalString) {
+  ManualGCScope manual_gc_scope;
   i::FLAG_stress_compaction = false;
   i::FLAG_gc_global = false;
   int dispose_count = 0;
@@ -812,6 +813,7 @@ THREADED_TEST(ScavengeExternalString) {
 
 
 THREADED_TEST(ScavengeExternalOneByteString) {
+  ManualGCScope manual_gc_scope;
   i::FLAG_stress_compaction = false;
   i::FLAG_gc_global = false;
   int dispose_count = 0;

test/cctest/test-strings.cc

@@ -1202,7 +1202,7 @@ TEST(InternalizeExternal) {
   Factory* factory = isolate->factory();
   // This won't leak; the external string mechanism will call Dispose() on it.
   OneByteVectorResource* resource =
-      new OneByteVectorResource(i::Vector<const char>("prop", 4));
+      new OneByteVectorResource(i::Vector<const char>("prop-1234", 9));
   {
     v8::HandleScope scope(CcTest::isolate());
     v8::Local<v8::String> ext_string =
@@ -1211,11 +1211,13 @@ TEST(InternalizeExternal) {
     Handle<String> string = v8::Utils::OpenHandle(*ext_string);
     CHECK(string->IsExternalString());
     CHECK(!string->IsInternalizedString());
-    CHECK(isolate->heap()->InNewSpace(*string));
+    CHECK(!isolate->heap()->InNewSpace(*string));
+    CHECK_EQ(
+        isolate->factory()->string_table()->LookupStringIfExists_NoAllocate(
+            *string),
+        Smi::FromInt(ResultSentinel::kNotFound));
     factory->InternalizeName(string);
-    CHECK(string->IsThinString());
-    CcTest::CollectGarbage(i::NEW_SPACE);
-    CcTest::CollectGarbage(i::NEW_SPACE);
+    CHECK(string->IsExternalString());
     CHECK(string->IsInternalizedString());
     CHECK(!isolate->heap()->InNewSpace(*string));
   }